First measurement of CP-violation using B 0 s K 0 K 0 decays

Transcription

1 First measurement of CP-violation using B s K K decays University of Cambridge On behalf of the LHCb collaboration Precision measurement of CP-violation in B s J/ψ K + K decays - PRL (215) Measurement of CP-violation in Bs φφ decays - PRD (214) First measurement of the CP-violating phase φ d d s LHCb-PAPER CERN LHC seminar 21 st November 217 in B s (K + π )(K π + ) decays NEW

2 2/3 Why is the universe matter dominated? Sakharov Conditions: 1.Baryon Number Violation 2.C and CP violation 3.Interactions out of thermal equilibrium I We live in a matter (and photon) dominated universe: nb /nγ 1 1 I CP-violation is a crucial ingredient to this problem I But CP-violation in the SM only accounts for 1 2 I There must be new physics and new sources of CP-violation

3 3/3 How to find New Physics at the LHC? High energy frontier Direct observation E=mc 2 Precision frontier Indirect effects NP? Require E > MC 2 for direct production New particles effect loop processes Most HEP direct discoveries have been preceeded by indirect evidence first! If we don t see New Physics directly at the LHC can indirect evidence guide us where to look (or what to build) next?

4 flavor flavor eigenstates CKM eigenstates matrix 1. Flavour Physics and CP-violation 4/3 mass mass eigenstates eigenstates Cabibbo Cabibbo In the SM quarks can change flavour by emission of a W ± boson Kobayashi Kobayashi matrix matrix elements So must elements also determine change determine charge transition (i.e. transition probabilities: from up-type probabilities: to down-type or vice-versa) Maskawa Maskawa The probability for such a transition is governed by the elements of the 3 3 unitary CKM matrix Marseille, March Marseille, 215March 215 T.M. Karbach T.M. / CERN Karbach / LHCb / CERN / LHCb CKM matrix d s b = flavour eigenstates V ud V us V ub V cd V cs V cb V td V ts V tb d s b mass eigenstates

5 flavor flavor eigenstates CKM eigenstates matrix 1. Flavour Physics and CP-violation 4/3 mass mass eigenstates eigenstates Cabibbo Cabibbo In the SM quarks can change flavour by emission of a W ± boson Kobayashi Kobayashi matrix matrix elements So must elements also determine change determine Maskawa charge transition (i.e. transition probabilities: from up-type probabilities: to down-type or vice-versa) Maskawa The probability for such a transition is governed by the elements of the 3 3 unitary CKM matrix It exhibits a clear hierarchy Marseille, March Marseille, 215March 215 T.M. Karbach T.M. / CERN Karbach / LHCb / CERN / LHCb CKM hierarchy V = V ud V us V ub V cd V cs V cb V td V ts V tb

6 flavor flavor eigenstates CKM eigenstates matrix 1. Flavour Physics and CP-violation 4/3 mass mass eigenstates eigenstates Cabibbo Cabibbo In the SM quarks can change flavour by emission of a W ± boson Kobayashi Kobayashi matrix matrix elements So must elements also determine change determine Maskawa charge transition (i.e. transition probabilities: from up-type probabilities: to down-type or vice-versa) Maskawa The probability for such a transition is governed by the elements of the 3 3 unitary CKM matrix It exhibits a clear hierarchy Contains the only source of CP-violation in the SM (i.e. if Λ QCD = m ν = ) Marseille, March Marseille, 215March 215 T.M. Karbach T.M. / CERN Karbach / LHCb / CERN / LHCb Wolfenstein parametrisation V ud V us V ub V = V cd V cs V cb = V td V ts V tb 1 λ 2 /2 λ Aλ 3 (ρ iη) λ 1 λ 2 /2 Aλ 2 Aλ 3 (1 ρ iη) Aλ 2 1 +O(λ 4 )

7 1. Flavour Physics and CP-violation 5/3 CKM matrix Unitarity imposes several conditions which give rise to unitarity triangles Wolfenstein parametrisation V ud V us V ub V = V cd V cs V cb = V td V ts V tb 1 λ 2 /2 λ Aλ 3 (ρ iη) λ 1 λ 2 /2 Aλ 2 Aλ 3 (1 ρ iη) Aλ O(λ 4 ) 1.5 B unitarity triangle V ud V ub + V cd V cb + V td V tb = (, ) 1..5 excluded area has CL >.95 sin 2β ε K α γ & m s m d m d V udv ub V cdv cb V td V tb V cd V cb η. -.5 α V ub γ excluded at CL >.95 β α -1. CKM f i t t e r ICHEP 16 γ ε K sol. w/ cos 2β < (excl. at CL >.95) (, ) (1, ) ρ

8 1. Flavour Physics and CP-violation 5/3 CKM matrix Unitarity imposes several conditions which give rise to unitarity triangles Wolfenstein parametrisation V ud V us V ub V = V cd V cs V cb = V td V ts V tb 1 λ 2 /2 λ Aλ 3 (ρ iη) λ 1 λ 2 /2 Aλ 2 Aλ 3 (1 ρ iη) Aλ O(λ 4 ) B s unitarity triangle V usv ub + V csv cb + V tsv tb = VusVub VcsVcb (, ) (, ) NOT TO SCALE (1, ) s V tsvtb V csvcb sb η excluded at CL >.95 m d ε K CKM f i t t e r ICHEP 16 & m s m d α ε K γ γ V ub β s excluded area has CL >.95 β s α sin 2β ρ sb s

9 Neutral meson mixing 1. Flavour Physics and CP-violation 6/3 b u, c, t s b W + s Bs s W ± W ± u, c, t B s b Bs s W B s b u, c, t u, c, t The physical mass eigenstates are admixtures of the weak eigenstates B s L,H = p B s q B s with mass difference, m, and width difference, Γ. If CP is conserved in mixing then = 1 States evolve with time according to Schrödinger s equation, i ( ) ( B s (t) t B = M i ) ( ) B s(t) 2 Γ s (t) B s(t) p q SM prediction and experimental value for CP violation in B s mixing is - [arxiv: ], [arxiv: ]

10 1. Flavour Physics and CP-violation 7/3 How does CP-violation manifest itself? Must have two interfering amplitudes with different strong (δ) and weak (φ) phases For a B s decay to a CP-eigenstate, f, CP-violation effects depend on λ = q p Ā f A f

11 1. Flavour Physics and CP-violation 7/3 How does CP-violation manifest itself? Must have two interfering amplitudes with different strong (δ) and weak (φ) phases For a B s decay to a CP-eigenstate, f, CP-violation effects depend on λ = q p Ā f A f CPV in decay: P(B s f ) P(B s f ) Ā f /A f = 1 B s A 1 A 2 dec CPV in decay f CP B s Ā 1Ā2 dec

12 1. Flavour Physics and CP-violation 7/3 How does CP-violation manifest itself? Must have two interfering amplitudes with different strong (δ) and weak (φ) phases For a B s decay to a CP-eigenstate, f, CP-violation effects depend on λ = q p Ā f CPV in decay: CPV in mixing: P(Bs f ) P(B s f ) P(Bs B s) P(B s Bs ) Ā f /A f = 1 q/p = 1 A f B s p q, m, A 1 A 2 dec CPV in decay f CP mix B s Ā 1Ā2 dec

13 1. Flavour Physics and CP-violation 7/3 How does CP-violation manifest itself? Must have two interfering amplitudes with different strong (δ) and weak (φ) phases For a B s decay to a CP-eigenstate, f, CP-violation effects depend on λ = q p Ā f CPV in decay: CPV in mixing: P(Bs f ) P(B s f ) P(Bs B s) P(B s Bs ) Ā f /A f = 1 q/p = 1 A f B s p q, m, A 1 A 2 dec CPV in interference CPV in decay s = mix 2 dec f CP mix B s Ā 1Ā2 dec CPV in the interference between decay and mixing: P(B s f ) P(B s B s f ) arg(λ)

14 7/3 1. Flavour Physics and CP-violation 1. Flavour Physics and CP-violation How does CP-violation manifest itself? 9/3 How does CP-violation manifest itself? 1/ Flavour and CP-violation 1. Flavour Physics Physics and CP-violation in B decay: system this phase InCPV B Insystem this phase is 2 is 2! f ) 6= dec Vubq -.5, 2 γ β γ md α α α p β CPV in interference η η η..5.5 md md m, Vub α α s -.5 = mix CKM fitter ICHEP CKM mix fitter ICHEP ρ ρ α. in decay CPV fcp A 1-.1 A s β s dec fitter B s α α β ICHEP 16 CKM ε fki t t e r εk βs βs γ -.5 CKM 2. Vub Vub γ sol. w/ cos 2 β <sol. w/ cos 2 β < (excl. at CL >.95) (excl. at CL >.95) γ md & m smd & ms mdα εk εk γ γ area has CL >.95 excluded area hasexcluded CL >.95 γ.95 α.95 εk εk. 1 K L> L> = ε1 at C at C L> L> Bs AA sin 2β sin 2β.5 εk uded excl uded excl at C md & mmsd & ms s P(Bs! B s ) 6= P(B s! Bs ).1.1 q/p I uded γ at C γ I excl excluded area has CL >.95 excluded area has CL >.95 uded 6= 1 excl I1.5 A 1.5 f /Af in Bsmixing: system this phase InCPV BsInsystem this phase is 2is s 2! f ) P(B s sb I P(B s η I Must have two interfering amplitudes with di erent strong ( ) and weak ( ) phases Make blocks Make blocks q A f For Bs! f decay, CP-violation e ects depend on = p Af sb I sin 2β sin 2β dec ICHEP ρ sb ρ sb CPV in the interference between decay and mixing: I I

15 2. Status of φs 8/3 Sensitivity to φ s SM predicts: φ s = (.37 ±.6) rad [arxiv: ] Small but non-zero Golden mode: B s J/ψ K + K - [Phys. Rev. Lett. 114 (215) 4181] B s b s (a) Only for b c cs transitions (φ c c W φ s = φ SM }{{} 2β s + φ peng + φ NP s c c s J/ψ h φ + h s ) + B s b s Colour singlet exchange ū, c, t (b) W c c s s J/ψ φh + h Estimate φ peng.3 [JHEP 11 (215) 82] (B J/ψ ρ, B s J/ψ K )

16 2. Status of φs 9/3 Current status World average for these modes currently dominated by LHCb Consistent with both the SM and zero - [arxiv: ] φ c s c (SM) = (.37 ±.6) rad φ c s c (WA) = (.21 ±.31) rad Γs[ps 1 ] Combined ATLAS 19.2 fb 1 SM D 8 fb 1 CMS 19.7 fb 1 LHCb 3 fb 1 HFLAV Summer % CL contours ( log L = 1.15) CDF 9.6 fb [rad] φ c cs s

17 2. Status of φs 1/3 B s φφ decays Pure penguin decay - b ss s transition New Physics can be significantly enhanced Purely hadronic final state The φ resonance is very narrow B s φφ B s φ s s s = (.17 ±.15 ±.3) rad [Phys. Rev. D (214)]

18 B s (K + π )(K π + ) decays 2. Status of φs 11/3 Pure penguin decay - b sd d transition New Physics can be significantly enhanced and entirely different from Bs J/ψ φ and Bs φφ Expect similar statistical precision to Bs φφ CPV in decay is also possible B s K K B s φ d d s =? LHCb-PAPER K K Experimentally challenging: Low branching fraction (1 times smaller than B s J/ψ φ) Purely hadronic final state K is fairly wide (several resonant and non-resonant components) Several peaking backgrounds φ c c s φ s s s φ d d s

19 Ingredients required for a φ s analysis 2. Status of φs 12/3 In the simplest case, and only if there is no CP-violation in decay, the time-dependent CP-asymmetry A CP (t) = Γ(B s f ) Γ(B s f ) Γ(B s f ) + Γ(B s f ) = η f sin(φ s) sin( m st) Experimentally A CP (t) (1 2w)e 1 2 m2 s σ2 t η f sin(φ s) sin( m st) w: Probability the initial B flavour was tagged incorrectly σ t: Decay-time resolution η f : CP-eigenvalue = angular analysis Important requirements Good decay time resolution Good flavour tagging Sufficient statistics for an angular analysis Good particle identification

20 3. The LHCb experiment 13/3 LHCb Detector Copius production of B +, B, B s, Λ b (1K bb/ s) IP resolution 2µm p resolution.5% Year R L (fb 1 ) resolution 45 fs Particle ID: (K) 95% Mis-ID: p(! K) 5% LHCb performance - [Int. J. Mod. Phys. A3, (215) 15322]

21 4. The Bs (K + π )(K π + ) decay decay The Bs K Kof Overview the 14/3 decay Bs! K K Interference between Bs K K and Bs B s K K I where K K + π and K K π + Channel Bs! K (892)K phase (892) (892): I Gives access to CP-violating φsd d optimal decay for the detection I discovered by LHCb in [Phys. Lett.time B79 (212) 5] offirst New Physics, by measuring dependent CP asymmetries. I Update in [JHEP 7 (215) 166] I Discussed extensively in the literature as a promising mode for New Physics I I Fleisher et. al. [Phys. Lett. phase, B66 (28) 212] CP violating weak s, originating from the interference [Phys. Rev. Lett.1 (28) 3182] I between decay BRev. B s(212) mixing. Descotes-Genon et. al.and [Phys. 341 ] s D85 he Bs! K K decay I Ciuchini et. al. Gluonic penguin decay. New particles may[phys. enter the loopb717 (212) 43] I Bhattacharya et. al. Lett. Combination of CP eigenstates in the final state. =) Interference between Bs /B s mixing and decay. =) Accessible CP violating phase s. SM expectations: 1 s Related via U-spin to the decay B! K K. =) Potential control over the theoretical uncertainties. Previous published papers (no measurement of I λ = SM expectation: ps ) A f 1 ), LHCb q Af Collaboration, 212. expectations First observation of the decay Bs! K K (35 pb Standard Model 1 Measurement of CP asymmetries and polarisation fractions in Bs! K K decays (1 fb 1Kenzie ), LHCb Collaboration, 215. Matthew I φds d = φmix 2φdecay

22 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 15/3 Increasing the statistics available Use a wide m(kπ) mass range: MeV/c 2 π + ) [MeV/c 2 ] m(k LHCb Preliminary LHCb LHCb-PAPER m(k + π ) [MeV/c 2 ] Weighted candidates

23 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 15/3 Increasing the statistics available Use a wide m(kπ) mass range: MeV/c 2 Vector:K (892) π + ) [MeV/c 2 ] m(k LHCb LHCb Preliminary LHCb-PAPER m(k + π ) [MeV/c 2 ] Weighted candidates

24 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 15/3 Increasing the statistics available Use a wide m(kπ) mass range: MeV/c 2 Vector:K (892) Tensor:K2 (143) π + ) [MeV/c 2 ] m(k LHCb LHCb Preliminary LHCb-PAPER m(k + π ) [MeV/c 2 ] Weighted candidates

25 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 15/3 Increasing the statistics available Use a wide m(kπ) mass range: MeV/c 2 Scalar:(K ± ) Vector:K (892) Tensor:K 2 (143) π + ) [MeV/c 2 ] m(k This gives 3 3 = 9 possible decays A single phase, φ d d s, is used for all LHCb LHCb Preliminary LHCb-PAPER Scalar description from Pelaez et. al. [Phys. Rev. D 93 (216) 7425] m(k + π ) [MeV/c 2 ] Weighted candidates

26 Building the decay model 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 16/3 Arbitrary Scale Illustrative Plots Arbitrary Scale Illustrative Plots m(k + π ) [MeV/c 2 ] Decay m(k π + ) [MeV/c 2 ] Polarization Amplitudes B s K (892) K (892) VV, VV, VV

27 Building the decay model 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 16/3 Arbitrary Scale Illustrative Plots Arbitrary Scale Illustrative Plots m(k + π ) [MeV/c 2 ] Decay Bs (K + π ) (K π + ) m(k π + ) [MeV/c 2 ] Polarization Amplitudes SS B s K (892) K (892) VV, VV, VV

28 Building the decay model 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 16/3 Arbitrary Scale Illustrative Plots Arbitrary Scale Illustrative Plots m(k + π ) [MeV/c 2 ] Decay Bs (K + π ) (K π + ) Bs (K + π ) K (892) Bs K (892) (K π + ) m(k π + ) [MeV/c 2 ] Polarization Amplitudes SS SV VS B s K (892) K (892) VV, VV, VV

29 Building the decay model 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 16/3 Arbitrary Scale Illustrative Plots Arbitrary Scale Illustrative Plots m(k + π ) [MeV/c 2 ] Decay Bs (K + π ) (K π + ) Bs (K + π ) K (892) Bs K (892) (K π + ) m(k π + ) [MeV/c 2 ] Polarization Amplitudes SS SV VS B s K (892) K (892) VV, VV, VV B s K 2 (143) K 2 (143) TT, TT 1, TT 1, TT 2, TT 2

30 Building the decay model 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 16/3 Arbitrary Scale Illustrative Plots Arbitrary Scale Illustrative Plots m(k + π ) [MeV/c 2 ] Decay Bs (K + π ) (K π + ) Bs (K + π ) K (892) Bs K (892) (K π + ) m(k π + ) [MeV/c 2 ] Polarization Amplitudes SS SV VS Bs K (892) K (892) VV, VV, VV Bs K (892) K 2 (143) VT, VT, VT Bs K2 (143) K (892) TV, TV, TV Bs K 2 (143) K 2 (143) TT, TT 1, TT 1, TT 2, TT 2

31 Building the decay model 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 16/3 Arbitrary Scale Illustrative Plots Arbitrary Scale Illustrative Plots m(k + π ) [MeV/c 2 ] m(k π + ) [MeV/c 2 ] Decay Polarization Amplitudes Bs (K + π ) (K π + ) SS Bs (K + π ) K (892) SV Bs K (892) (K π + ) VS Bs (K + π ) K 2 (143) ST Bs K2 (143) (K π + ) TS Bs K (892) K (892) VV, VV, VV Bs K (892) K 2 (143) VT, VT, VT Bs K2 (143) K (892) TV, TV, TV Bs K 2 (143) K 2 (143) TT, TT 1, TT 1, TT 2, TT 2

32 Building the decay model 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 16/3 Arbitrary Scale Illustrative Plots Arbitrary Scale Illustrative Plots m(k + π ) [MeV/c 2 ] m(k π + ) [MeV/c 2 ] Decay Polarization Amplitudes Bs (K + π ) (K π + ) SS Bs (K + π ) K (892) SV Bs K (892) (K π + ) VS Bs (K + π ) K 2 (143) ST Bs K2 (143) (K π + ) TS Bs K (892) K (892) VV, VV, VV Bs K (892) K 2 (143) VT, VT, VT Bs K2 (143) K (892) TV, TV, TV Bs K 2 (143) K 2 (143) TT, TT 1, TT 1, TT 2, TT 2

33 Building the decay model II 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 17/3 Factorise the time-dependent probability p(t, Ω) ij K ij (t) }{{} time dep F ij (Ω) }{{} ang/mass dep

34 Building the decay model II 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 17/3 Factorise the time-dependent probability p(t, Ω) ij K ij (t) }{{} time dep F ij (Ω) }{{} ang/mass dep Time-dependent terms K ij (t) =R(t, ) e st + a ij cosh( 1 } 2 st)+b ij sinh( 1 2 st) + (c ij cos( m s t)+d ij sin( m s t)) {z {z 2 {z } decay time flavour mixing + resolution tagging +decay Coefficients contain dependence on physical parameters 2 a ij = A 1+ 2 i A j + i j 2 A ī A j, b ij = 2 c ij = A 1+ 2 i A j i j 2 A ī A j, d ij = j e i s A i A j + ie i s A ī A j, 2 i 1+ 2 j e i s A i A j i e i s A ī A j

35 Building the decay model II 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 17/3 Factorise the time-dependent probability p(t, Ω) ij K ij (t) }{{} time dep F ij (Ω) }{{} ang/mass dep Angular and mass dependence Ω = (cos θ 1, cos θ 2, ϕ, m 1, m 2 ) F ij ( ) = j1,j 2,h(cos 1, cos 2, ') j 1,j 2,h(cos 1, cos 2, ') {z } angular terms M j1 (m 1 )M j2 (m 2 ) M j 1 (m 1)M j 2 (m 2) {z } mass terms F j1,j 2,h(m 1,m 2 )F j 1,j 2,h(m 1,m 2 ) {z } ang. mom. factors

36 Building the decay model II 4. The B s (K+ π )(K π + ) decay 4.1 The Decay Model 17/3 Factorise the time-dependent probability p(t, Ω) ij K ij (t) }{{} time dep F ij (Ω) }{{} ang/mass dep Angular and mass dependence Ω = (cos θ 1, cos θ 2, ϕ, m 1, m 2 ) F ij ( ) = j1,j 2,h(cos 1, cos 2, ') j 1,j 2,h(cos 1, cos 2, ') {z } angular terms θ 1 K + ϕ K θ2 π B s π +

37 Selecting the signal 4. The B s (K+ π )(K π + ) decay 4.2 Signal isolation 18/3 Remove unwanted backgrounds: Use particle identification requirements from Cherenkov detectors Boosted Decision Tree to reject combinatorial background Mass vetoes for unwanted contributions Background (train) Signal (train) Background (test) Signal (test) KS-Test=.76 KS-Test=.34 Probability LHCb Unofficial bdtoutput Residual LHCb Unofficial Before Λ B veto After Λ B veto m(pπ K π + ) [MeV]

38 Selecting the signal 4. The B s (K+ π )(K π + ) decay 4.2 Signal isolation 19/3 Remove unwanted backgrounds: Use particle identification requirements from Cherenkov detectors Boosted Decision Tree to reject combinatorial background Mass vetoes for unwanted contributions Use splot procedure to subtract background Candidates / 8 MeV/c LHCb Preliminary LHCb-PAPER Bs Bd Bd + (K π )(K π + ) + (K π )(K π + ) + + (K π )(K K ) + Bd (K π )(π π + ) Bs + + (K π )(K K ) Λb (p π )(K π + ) Partially reconstructed Combinatorial Total PDF Data Candidates / 8 MeV/c LHCb Preliminary LHCb-PAPER m(k π K π + ) [MeV/c 2 ] m(k π K π + ) [MeV/c 2 ] N S = 68 ± 84 events

39 Kinematic acceptance 4. The B s (K+ π )(K π + ) decay 4.3 Acceptance and resolution 2/3 Detector geometry and selection criteria introduce non-uniform acceptance Introduce event weights in the normalisation term of the model Create a 5D efficiency map for angular terms, F ij (Ω) Scaled acceptance integral LHCb simulation cos(θ 1) Scaled acceptance integral LHCb simulation cos(θ 2) Scaled acceptance integral LHCb simulation ϕ [rad] Scaled acceptance integral LHCb simulation m(k + π ) [MeV/c 2 ] Scaled acceptance integral LHCb simulation m(k π + ) [MeV/c 2 ]

40 4. The B s (K+ π )(K π + ) decay 4.3 Acceptance and resolution 21/3 Kinematic and decay-time acceptance Detector geometry and selection criteria introduce non-uniform acceptance Model the decay-time acceptance parametrically using cubic splines Scaled acceptance integral LHCb simulation t [ps]

41 Decay-time resolution 4. The B s (K+ π )(K π + ) decay 4.3 Acceptance and resolution 22/3 Time-dependent decay rate of Bs d dt / X apple R(t, t) e st 1 a ij cosh 2 ij z(pv) 1µm z(b s) 3µm PV B s Decay-time resolution d 1cm Modelled as a Gaussian 1 st + b ij sinh 2 K + K + t = d m(b s) p(b s) st + c ij cos( m s t)+d ij sin( m s t) Candidates Candidates / (.5 ps) / (.5 ps) Example Plot From LHCb-PAPER LHCb LHCb < t > 45fs Decay time [ps] -4 True decay-time resolution, σ t, as a function of the estimated decay-time resolution, δ t, obtained from simulation using a linear calibration

42 Flavour tagging 4. The B s (K+ π )(K π + ) decay 4.3 Acceptance and resolution 23/3 Use both Flavour same side Tagging: (SS) and Determine opposite side B production (OS) taggers flavours calibrated on real data PV SS Pion SS Kaon Signal Decay Same Side Opposite Side OS Kaon OS Vertex Charge Effective Fraction with tagging power tagging decision Ulrich Eitschberger Updates on Flavour Tagging 72 nd LHCb week June 19th, 214 Calibrated mistag probability e = tag (1 2!) 2 OS Muon OS Electron 3/2 Combined Tagging Performance: ɛ tag = (75.6 ±.6)% and ɛ eff = (5.15 ±.14)%

43 4. The B s (K+ π )(K π + ) decay 4.3 Acceptance and resolution 24/3 Systematics Table of systematic uncertainties Parameter φ d d s [rad] λ Yield and shape of mass model.12.1 Signal weights of mass model.12.7 TD fit procedure.6.2 TD fit parametrisation Acceptance weights (simulated sample size) Other acceptance and resolution effects.63.8 Production asymmetry.2.2 Total Only shown for the CP observables, φ d d s and λ There are 39 physical observables in total

44 4. The B s (K+ π )(K π + ) decay 4.4 Results 25/3 Fit Projections Nominal fit took too long on a conventional CPU Novel implementation in GPUs with Ipanema ([arxiv: ]) - 6 faster m s, Γ s, Γ s are constrained to their known values Candidates / 34 MeV/c LHCb Preliminary LHCb-PAPER Candidates / 34 MeV/c LHCb Preliminary LHCb-PAPER Candidates / 1 ps LHCb Preliminary LHCb-PAPER Candidates / m(k + π ) [MeV/c 2 ] andidates / 34 MeV/c 2 12 Candidates / m(k π + ) [MeV/c 2 ] t [ps] LHCb LHCb LHCb Preliminary 5 Preliminary 5 Preliminary LHCb-PAPER LHCb-PAPER LHCb-PAPER Total PDF 4 4 Data 3 SS 3 3 LHCb Total PDF 8 2 SV+VS Data 1 1 SS 1 LHCb VV cos(θ 1) 6 Total PDF SV+VS cos(θ 2) ST+TS ϕ [rad] dates / 34 MeV/c 2 6 Data SS 4 LHCb Total PDF SV+VS SS VV Candidates /.45 rad ST+TS VT+TV Data VT+TV TT LHCb

45 4. The B s (K+ π )(K π + ) decay 4.4 Results 26/3 Table 4: Results of the fit to the data. The first uncertainty is statistical and the second Numerical Results uncertainty is systematic. The systematic uncertainties are discussed in Sec. 9 Parameter Value Common parameters d d s [rad].1 ±.13 ± ±.34 ±.89 Bs! K (892) K (892) (VV) f VV.67 ±.4 ±.24 fl VV.28 ±.32 ±.46 fk VV.297 ±.29 ±.42 VV k [rad] 2.4 ±.11 ±.33 [rad] 2.62 ±.26 ±.64 VV? Single S-wave (SV and VS) f SV.329 ±.15 ±.71 f VS.133 ±.13 ±.65 SV [rad] 1.31 ±.1 ±.35 VS [rad] 1.86 ±.11 ±.41 Double SS-wave (SS) f SS.225 ±.1 ±.69 SS [rad] 1.7 ±.1 ±.4 Single P -wave decays (ST and TS) f ST.14 ±.6 ±.31 f TS.25 ±.7 ±.33 ST [rad] 2.3 ±.4 ± 1.69 TS [rad].1 ±.26 ±.82 Parameter Value Single D-wave (VT and TV) f VT.16 ±.16 ±.49 fl VT.911 ±.2 ±.165 fk VT.12 ±.8 ±.53 f TV.36 ±.14 ±.48 fl TV.62 ±.16 ±.25 fk TV.24 ±.1 ±.143 VT [rad] 2.6 ±.19 ± 1.17 VT k [rad] 1.8 ±.4 ± 1.16 VT? [rad] 3.8 ±.29 ±.97 TV [rad] 1.91 ±.3 ±.8 TV k [rad] 1.9 ±.19 ±.55 TV? [rad].2 ±.4 ± 1.1 Double DD-wave (TT) f TT.11 ±.3 ±.7 fl TT.25 ±.14 ±.18 f TT k1.17 ±.11 ±.14 f TT?1.3 ±.18 ±.21 f TT k2.15 ±.33 ±.17 TT [rad] 1.3 ±.5 ± 1.8 TT k1 [rad] 3. ±.29 ±.57 TT [rad]?1 2.6 ±.4 ± 1.5 TT k2 [rad] 2.3 ±.8 ± 1.7 TT [rad].7 ±.6 ± 1.3? Time-dependent fit procedure An ensemble of pseudoexperiments are generated to estimate the bias on the parameters

46 4. The B s (K+ π )(K π + ) decay 4.4 Results 26/3 Table 4: Results of the fit to the data. The first uncertainty is statistical and the second Numerical Results Make block Summary uncertainty 1. The is systematic. B The systematic uncertainties are discussed in Sec. 9 s! (K+ )(K + )decay 1.4 Results 14/14 Parameter Value Common parameters d d s [rad].1 ±.13 ± ±.34 ±.89 Bs! K (892) K (892) (VV) f VV.67 ±.4 ±.24 fl VV.28 ±.32 ±.46 fk VV.297 ±.29 ±.42 VV k [rad] 2.4 ±.11 ±.33 VV? [rad] 2.62 ±.26 ±.64 Single S-wave (SV and VS) f SV.329 ±.15 ±.71 f VS.133 ±.13 ±.65 SV [rad] 1.31 ±.1 ±.35 VS [rad] 1.86 ±.11 ±.41 Double SS-wave (SS) f SS.225 ±.1 ±.69 SS [rad] 1.7 ±.1 ±.4 Single P -wave decays (ST and TS) f ST.14 ±.6 ±.31 f TS.25 ±.7 ±.33 ST [rad] 2.3 ±.4 ± 1.69 TS [rad].1 ±.26 ±.82 Parameter Value Single D-wave (VT and TV) f VT.16 ±.16 ±.49 fl VT.911 ±.2 ±.165 fk VT.12 ±.8 ±.53 f TV.36 ±.14 ±.48 fl TV.62 ±.16 ±.25 fk TV.24 ±.1 ±.143 VT [rad] 2.6 ±.19 ± 1.17 VT k [rad] 1.8 ±.4 ± 1.16 VT? [rad] 3.8 ±.29 ±.97 TV [rad] 1.91 ±.3 ±.8 TV k [rad] 1.9 ±.19 ±.55 TV? [rad].2 ±.4 ± 1.1 Double DD-wave (TT) f TT.11 ±.3 ±.7 fl TT.25 ±.14 ±.18 f TT k1.17 ±.11 ±.14 f TT?1.3 ±.18 ±.21 f TT k2.15 ±.33 ±.17 TT [rad] 1.3 ±.5 ± 1.8 TT k1 [rad] 3. ±.29 ±.57 TT [rad]?1 2.6 ±.4 ± 1.5 TT k2 [rad] 2.3 ±.8 ± 1.7 TT [rad].7 ±.6 ± 1.3 I Measure CP-averaged fractions, f, andstrong phase di erences,, for 19 di erent amplitudes I I I In particular: I f VV I I L =.28 ±.32 ±.46 -smallvalue(asinprevious-[jhep 7 (215) 166]) f SS =.225 ±.1 ±.69 -largevalue f VV =.67 ±.4 ±.24 -smallvalue Measure CP-violation parameters d d I s =(.1 ±.13 ±.14) rad I =(1.35 ±.34 ±.89) SM wins again!? Time-dependent fit procedure 352 An ensemble of pseudoexperiments are generated to estimate the bias on the parameters

47 5. Summary and Outlook 27/3 Future prospects LHCb Upgrade will be installed in LS2 unning a full software trigger Ready for operation in Run 3 ave access to full events information, & being able to exploit lifetime & decay opology Completely information, at redesigned earliest trigger tracking level will systems bring big gains in efficiency. Redesigned readout for all subsystems Different output rate options Run 1 efficiency ffect will be most marked for hadronic decays, where efficiency increases of t least factor 2 can be expected. Such a trigger can also run at higher lumi, contrast to existing L, which would saturate and bring no net benefit. 21

48 Beyond Run 4? 5. Summary and Outlook 28/3 LS2 starting in 219 Expression of interest submitted LS3 LHC: for starting Phase-II in 224 upgrade LHC Injectors LHC Injectors LHC Injectors LHC roadmap: according to MTP V1 Injectors: in Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Run 3 Run 2 => 24 months + 3 months BC => 3 months + 3 months BC => 13 months + 3 months BC PHASE 1 LS Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Run Q2 Q34 Q4 Q1 Q2 Q3 Q4 Run 3 LS 3 Run 4 PHASE Q1 Q2 LS Q34 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2LS Q3 5Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 LS 4 Run 5 LS 5 Physics Shutdown Beam commissioning Technical stop Expected luminosities Run 1 + Run 2 L 8.5 fb 1 Run 3 + Run 4 L 5 fb 1 Run 5 + L 3 fb 1

49 Current developments in B s J/ψ K + K 5. Summary and Outlook 29/3 Run 2 analysis of Bs J/ψ K + K is underway More than double the statistics of Run 1 (with just 215 and 216) σ stat.42 rad (Run 1:.49 rad) Run 2 analysis of B s φφ also underway Watch this space...

50 Summary and Outlook 5. Summary and Outlook 3/3 First ever measurement of φ d d s = (.1 ±.13 ±.14) rad Statistical Gluonic precision penguin similar decay. to New Bs particles φφ withmay a large enter systematic the loopcontribution The B s! K K decay Statistical Combination precisionof CP 2.5 eigenstates worse than inbthe s final J/ψ state. φ =) Interference between Dominant Bs / B s systematics mixing andarise decay. from=) limited Accessible MC statistics CP violating so are reducible phase s. SM expectations: 1 s Related via U-spin to the decay B! K K. =) Potential control over the At present no evidence of CP-violation in interference between Bs decay and mixing theoretical uncertainties. Currently all CP-measurements are consistent with the SM Previous published papers (no measurement of s) Let s hope we can break it in Run 2 and beyond! First observation of the decay B s! K K (35 pb 1 ), LHCb Collaboration, 212. THANK YOU! Measurement of CP asymmetries and polarisation fractions in B s! K K decays (1 fb 1 ), LHCb Collaboration, 215.